@Get()
 call(): Observable<string> {
   //呼叫使用一個策略，選定sayHi
   const pattern = { cmd: 'sayHi' };
   //由於send()要傳入兩個參數，pattern 和 data，data這邊給定空字串。
   const data = '';
   return this.client.send<string>(pattern, data);
 }

 @Get('broadcast')
 multicats() {
   return this.client.send<number>({ cmd: 'broadcast' }, {})
     .pipe(
       scan((a, b) => a + b),
       take(2),
     );
 }

 @Get('/rabbitMQ')
 callRabbitMQ(): Observable<string> {
   //呼叫使用一個策略，選定amqp
   const pattern = { cmd: 'amqp' };
   //send()要傳入兩個參數，pattern 和 data，pattern選擇哪種策略，data則是要傳遞的訊息。
   const data = 'use RabbitMQ';
   //透過RabbitMQ消息隊列方式傳遞訊息，注意queue要跟server.ts建立的RabbitMQServer的queue一樣
   this.client = new RabbitMQClient('amqp://rmtahlzz:[email protected]/rmtahlzz', 'example');
   return this.client.send<string>(pattern, data);
 }

 @Get()
 call(): Observable<number> {
   const pattern = { cmd: 'sum' };
   const data = [1, 2, 3, 4, 5];
   return this.client.send<number>(pattern, data);
 }

 @Get('broadcast')
 multicats() {
   return this.client
     .send<number>('broadcast.test', {})
     .pipe(scan((a, b) => a + b), take(2));
 }